As an aside, and it was mentioned above, but if you do go down a slope even on a gravel road, let alone a grassy hill, with weight in the FEL, you are in for the "wild ride", where the rear tires get light and slip on the ground, and if your not in 4wd when this happens, you go flying down the slope and picking up speed and the ONLY thing that can stop you is drop the bucket and anything on the 3pt hitch to drag on the ground, because brakes are NOT going to help you a bit as the tires contact patch is not making contact any more with the ground.
You can avoid this by making sure you stay in 4wd on slopes and also as pointed out above, by going down bad slopes backwards. And I know you are doing it now, but don't ever forget, the terms "low and slow". When you have a load in the FEL, keep it as low as safely possible. when moving and move slow. Raising the FEL is the number one reason for tractor roll overs. Remember that front axle, even on a 4 WD tractor is on a center pivot and you can roll over in a heartbeat with a high center of gravity which the FEL puts you on as soon as you raise it.